There's no theoretical limitation on such tactics. My own way of limiting this as DM is that if they're not animal companions and they're not acquired through Leadership, they count as party members for purposes of calculating XP for any combat they take part in.Kor said:I am not aware of any limitations of having trained animals -- ones you have trained via the Handle Animal skill. I'm not sure if it would work well with the rat swarm, but would it not be possible to simply designate the "lead wolf" of a wolf pack as your "animal companion", and the rest of the wolves would simply be "trained wolves"?

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.